Black crystals of the very rare mineral stibiocolumbite from Mesa Grande District, San Diego County, California, United States of America. — Photo: David Hospital · CC BY-SA 4.0
Stibiocolumbite
Stibiocolumbite is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula SbNbO₄.
It crystallizes in the orthorhombic crystal system (space group Pna2_1).
Key properties: Mohs hardness 5.5; specific gravity 5.68; Pale yellow to yellow-brown streak; Resinous to adamantine luster; optically biaxial.
IMA symbol Sclb, grandfathered status — known before the IMA’s founding, named in 1915.
Found as a rare accessory mineral in complex granite pegmatites.
It is found associated with Tourmaline, beryl, lepidolite (Mesa Grande district, California, USA).
The name comes from the Latin for antimony, STIBium, in its composition, and relation to columbite.